Data from: Illusory speeding-up and slowing-down of objects moving at constant speed emerges from natural motion detection algorithms

The footsteps illusion is a perceptual illusion in which two bars moving
at the same constant speed on a stripey background are seen as alternately
accelerating and decelerating like footsteps. The cortical mechanisms that
give rise to footsteps and similar illusions remain to be fully understood
and may reveal important neural computations. Using an implementation of
the biologically inspired correlational model of motion detection, the
2DMD, this study had three aims. First, reproducing perceptual speed
oscillations in model simulations. Second, mapping empirical reports of
multiple illusion configurations onto model outputs. Third, inferring from
the successful model, the role of multi-scale spatiotemporal channels in
perception. We developed a 2DMD implementation adding a global (single
value) frame-by-frame dynamic readout to quantify the continuous and
oscillating response components. We confirmed that an expected signature
oscillatory motion response corresponded to the footsteps illusion,
demonstrating that its amplitude varied according to empirically measured
illusion strength. We showed that with a global readout, the inherent
pattern and contrast dependence of correlation detectors is sufficient to
reproduce the surprising perceptual illusion. This evidence suggests
spacetime correlation may be a fundamental sensory computation. Across
species, filtering and global pooling operations might be adapted to
process various complex phenomena.